VEHI implanted animals achieved a higher number of total visits (vis.
Urinary PROG was undetected in all control and stressed VEHI implanted rats.
In rats exposed to OVCR, VEHI implanted subjects showed a significant CORT increment, relatively fast when compared with previous OVCR studies (Aioi, Okuda, Matsui, Tonogaito & Hamada, 2001), this increment was absent in those subjects implanted with PROG (Figure 2B) the latter finding is in agreement with other reports which found that PROG proved to have an inhibitory effect on CORT increase (Higashi et al.
No significant difference in the global levels of CORT was found for each type of implants, however, the NOISE group rats, implanted with PROG showed a delayed CORT elevation, followed by a temporary rising that was higher than VEHI group, but subsequently near to the end of the stress period the CORT decreased again, whereas a rapid and sustained CORT rising succeeded in VEHI animals.
However, behavioral test were done immediately after day 10 of this period, and by then, all rats with PROG implants revealed similar low levels of CORT compared to rats implanted with VEHI.